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  • AgentArmor teamTeam3d agoNeeds helpSolved

    Am I affected by MCP TypeScript SDK OAuth client could send credentials to an authorization server chosen…? What should I do?

    The SDK's OAuth client let the MCP server decide which authorization server received the client's OAuth credentials.

    Affected: @modelcontextprotocol/sdk 1.12.0 through 1.30.1; @modelcontextprotocol/client 2.0.0 through 2.1.0. Fixed in: @modelcontextprotocol/sdk 1.31.0; @modelcontextprotocol/client 2.2.0. What should you check, and what should you do about it?

    Full incident page with sources: https://agentarmorhq.com/incidents/2026/10/cve-2026-104850-mcp-typescript-sdk-modelcontextprotocol-sdk-and-modelcontextprotocol-client (opens external site)

    1 answer

    • Best answerAgentArmor teamTeamIncidents, compromised packages and supply chain3d ago

      Am I affected? Affected: @modelcontextprotocol/sdk 1.12.0 through 1.30.1; @modelcontextprotocol/client 2.0.0 through 2.1.0. Fixed in: @modelcontextprotocol/sdk 1.31.0; @modelcontextprotocol/client 2.2.0.

      • Check your version: run npm ls @modelcontextprotocol/sdk. Versions >= 1.12.0, < 1.31.0 of @modelcontextprotocol/sdk are affected.
      • Check your version: run npm ls @modelcontextprotocol/client. Versions >= 2.0.0, < 2.2.0 of @modelcontextprotocol/client are affected.

      What to do now

      1. Upgrade to the fixed version: run npm install @modelcontextprotocol/sdk@1.31.0 (first patched version 1.31.0).
      2. Upgrade to the fixed version: run npm install @modelcontextprotocol/client@2.2.0 (first patched version 2.2.0).
      3. Upgrade to @modelcontextprotocol/sdk 1.31.0 or later, or @modelcontextprotocol/client 2.2.0 or later, and @modelcontextprotocol/core 2.2.0 or later if you import it directly.
      4. Pass expectedIssuer to bundled providers, for example expectedIssuer: 'https://auth.example.com (opens external site)'.
      5. Add issuer to credentials saved without it, or clear them so users sign in again.
      6. If an affected client may have connected to an untrusted MCP server, rotate its client secret or signing key and revoke its tokens.

      General practice, not from the source: if the affected software could read tokens or credentials, rotate them after upgrading; pin versions and review changes before updating tools your agents run.

      Sources

      Full incident page: https://agentarmorhq.com/incidents/2026/10/cve-2026-104850-mcp-typescript-sdk-modelcontextprotocol-sdk-and-modelcontextprotocol-client (opens external site)

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